1. Field of the Invention
The invention is directed to phenyl-containing functional polysiloxanes and polycarbonate-polysiloxane copolymers made therefrom.
2. Background of the Invention
Polycarbonate polymers are useful in the manufacture of articles and components for a wide range of applications, including automotive parts such as headlights and windshields, as well as medical devices. However, many polycarbonate polymers are brittle especially at low temperatures. Polycarbonate copolymers containing polysiloxane blocks in particular have shown excellent low temperature impact properties, improved solvent resistance, inherent flame retardancy, improved hydrolytic resistance and heat aging characteristics and excellent processability. However, due to larger difference in refractive index between polycarbonate and polysiloxane blocks, the resulting copolymer is typically opaque unless the siloxane domains are very small. Though smaller domains can be produced by using the siloxane blocks with lesser D lengths (typically <30), the low temperature impact resistance improvement is compromised in such copolymer compositions.
Eugenol-terminated polymers are known in the art for various purposes, such as heat resistance, improved ductility and thermoprocessing, solvent resistance, and the like. It is also known that eugenol may be used as an end cap for polysiloxane polymers. For example, U.S. Pat. No. 5,661,202, EP0570208A2, U.S. Pat. No. 7,709,581B2, US2008/0081860A1 disclose eugenol-terminated fluids with different substituents in the backbone or pendant thereto.
Copolymers of polycarbonate and polysiloxane are also known in the art. For example, U.S. Pat. No. 6,576,735 discloses the preparation of polycarbonate-polysiloxane copolymeric compositions from 9,9-bis(4-hydroxy-3-methylphenyl)fluorene and phenyl-containing siloxanes as monomers. Polycarbonate from 9,9-Bis(4-hydroxy-3-methylphenyl)fluorene monomer results in rigid architecture as compared to polycarbonate from Bisphenol-A. It has been submitted that siloxane-containing comonomers impart moldability. U.S. Pat. No. 7,498,388B2 discloses the use of eugenol-terminated siloxane with smaller D chains to prepare PC-polysiloxane copolymer compositions with 3-5 wt % siloxane concentration with lower BY span (the difference between the yellowness index in transmission and the yellowness index in reflectance) that gives 100% ductility only up to −30 C. The resulting polymers exhibit reduced “edge haze” during formation of molded articles.
Several attempts have been made using eugenol-terminated siloxane (D length 45-50) to make transparent (low haze) polycarbonate-polysiloxane copolymers. For example, U.S. Pat. No. 5,530,083 discloses a multistep method of making transparent polycarbonate-polysiloxane copolymers. In a first step, oligomeric bisphenol polycarbonate are prepared by phosgenating bisphenol-A using phase transfer catalyst. In a second step, bisphenol chloroformates are reacted with bis(hydroxyaryl) siloxanes in the absence of phosgene. EPI654301A1 discloses the preparation of siloxane-bischloroformate in one step and addition of siloxane-BCF to polycarbonate synthesis process in the presence of recoverable catalysts.
There is a need for polycarbonate-polysiloxane copolymer compositions with improved optical clarity (high % transmission and low haze) with better low-temperature impact resistance. The present invention is believed to provide an answer to that need.